Multi-layer printed coil arrangement having variable-pitch printed coils

ABSTRACT

A printed coil assembly including a flexible dielectric material, a patterned top conductive layer formed on a top surface of the flexible dielectric material, and a patterned bottom conductive layer formed on a bottom surface of the flexible dielectric material. The patterned top conductive layer and the patterned bottom conductive layer form a plurality of printed coils arranged in a plurality of printed coil rollers concentrically arranged in a cylindrical shape. Each of the plurality of printed coils includes a top layer printed coil disposed within the patterned top conductive layer and a bottom layer printed coil disposed within the patterned bottom conductive layer. Coil pitches of the coils within each roller are chosen such that corresponding ones of the plurality of printed coils in adjacent rollers are axially aligned relative to a center of the cylindrical shape.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 62/971,848, entitled ACTUATOR SYSTEM INCLUDINGVARIABLE-PITCH PRINTED COILS, filed on Feb. 7, 2020, the disclosure ofwhich is incorporated herein by reference in its entirety for allpurposes.

FIELD

This disclosure relates generally to electromagnetic actuators and, moreparticularly, to coils for such actuators.

BACKGROUND

Moving coil technology works in both rotary and linear motors actuators.Within a moving coil actuator are permanent magnets generating amagnetic field. A moving coil resides in that field. Passing currentthrough the coil generates transverse motion of the coil and an outputshaft or shuttle to which the coil is coupled. The force of that outputis proportional to the number of coils turns and the magnetic fluxwithin the actuator as well as to the current. Providing more currentthrough the coil thus increases output force.

The introduction of high-strength neodymium magnets has greatly expandedthe applicability of moving-coil actuators in motion applications sinceactuators with these magnets are capable of outputting a high force (ortorque). The light moving mass of their coils make the actuators excelin many industrial applications because this allows, for example, highcycle rates—up to twice that of pneumatic or ball screw actuators. Inaddition, moving-coil actuators have long cycle life (up to 10 timesthat of pneumatic or ball screw linear actuators), and highrepeatability over each cycle.

However, wider implementation of moving coil actuators has been limitedby their high cost relative to actuators using pneumatic cylinders oractuators incorporating stepper-motor-based ball screw technologies.

SUMMARY

In one aspect the disclosure is directed to a printed coil assemblyincluding a flexible dielectric material, a patterned top conductivelayer formed on a top surface of the flexible dielectric material, and apatterned bottom conductive layer formed on a bottom surface of theflexible dielectric material. The patterned top conductive layer and thepatterned bottom conductive layer form a plurality of printed coilsarranged in a plurality of printed coil rollers disposed to beconcentrically arranged in a cylindrical shape. Each of the plurality ofprinted coils includes a top layer printed coil disposed within thepatterned top conductive layer and a bottom layer printed coil disposedwithin the patterned bottom conductive layer. A first coil pitch of afirst set of the plurality of printed coils within a first roller of theprinted coil rollers is less than a second coil pitch of a second set ofthe plurality of printed coils within a second roller of the pluralityof rollers such that corresponding ones of the plurality of printedcoils in the first and second rollers are axially aligned relative to acenter of the cylindrical shape.

The disclosure also relates to a printed coil arrangement which includesa flexible circuit material rolled into concentric printed coil rollers.Each of the plurality of concentric printed coil rollers includes aplurality of printed coils. A pitch of the plurality of printed coilswithin each one of the plurality of printed coil rollers is differentfrom a pitch of the plurality of printed coils within any other of theplurality of printed coil rollers. The pitches of the printed coilswithin each of the plurality of coil rollers are selected such thatcorresponding ones of the plurality of printed coils in each of theplurality of printed coil rollers are axially aligned relative to acenter of a cylindrical shape into which the flexible circuit materialis rolled. The printed coil arrangement further includes a bobbin and anadhesive layer. The adhesive layer is attached to an outer surface ofthe bobbin and a bottom surface of an innermost one of the plurality ofconcentric printed coil rollers.

In another aspect the disclosure pertains to a method of fabricating aprinted coil arrangement. The method includes applying, to a topconductive layer of a flexible circuit material and to a bottomconductive layer of a flexible circuit material, one or more masksdefining a desired printed coil circuit pattern where the desiredprinted coil circuit pattern includes multiple rollers having printedcoils of variable pitch. The flexible circuit material further includesa flexible dielectric layer sandwiched between the top conductive layerand the bottom conductive layer. The method further includes exposingunmasked portions of the top conductive layer of the flexible circuitmaterial and the bottom conductive layer of the flexible circuitmaterial to acid and removing the unmasked portions of the topconductive layer and the bottom conductive layer. Additional masks areapplied to the unmasked portions of the top conductive layer and thebottom conductive layer. The method further includes plating additionalconductive material onto the desired printed coil pattern and covering aconductive trace resulting from the plating with a printed screen. Oneof gold and a different conductive material is then plated onto theadditional conductive material of the conductive trace.

The disclosure further pertains to a method of fabricating a printedcoil arrangement. The method includes etching a flexible circuitmaterial into a plurality of coil rollers wherein each of the pluralityof coil rollers includes a plurality of printed coils and wherein apitch of the plurality of printed coils within each one of the pluralityof printed coil rollers is different from a pitch of the plurality ofprinted coils within any other of the plurality printed coil rollers.The pitches of the printed coils within each of the plurality of coilrollers are selected such that corresponding ones of the plurality ofprinted coils in each of the plurality of printed coil rollers areaxially aligned relative to a center of a cylindrical shape into whichthe flexible circuit material is rolled. The method further includesapplying an adhesive material to a bottom surface of the flexiblecircuit material. A first coil roller of the plurality of printed coilrollers is positioned on an outer surface of a bobbin and the first coilroller is bonded to the outer surface using the adhesive material. Theremaining rollers of the plurality of printed coil rollers are thenrolled onto the first coil roller. Adjacent printed coil rollers of theplurality of printed coil rollers are bonded to each other using theadhesive material, thereby creating a rolled and bonded printed coilcircuit. The method further includes curing the rolled and bondedprinted coil circuit in an oven.

In another aspect the disclosure is directed to a direct drive brushlessmotor including a plurality of rotational components having a centerrotation shaft circumscribed by a plurality of coils and a coiltermination plate configured to support the plurality of coils. Theplurality of coils includes a plurality of printed coils arranged inmultiple coil rollers wound around a bobbin wherein a first pitch of afirst set of the plurality of printed coils included within a first ofthe multiple coil rollers is different from a second pitch of a secondset of the plurality of coil rollers included within a second of themultiple coil rollers. A plurality of non-rotational components includea plurality of inner magnets and a plurality of outer magnets whereinthe plurality of outer magnets are positioned around the plurality ofcoils. A flex cable has one or more leads for providing electricalcurrent to one or more of the plurality of coils without the use ofbrushes.

This disclosure also concerns a direct drive brushless motor including aplurality of outer magnets arranged as a first Halbach cylinder. A coilassembly includes a plurality of coils surrounded by the plurality ofouter magnets wherein the plurality of coils are connected without theuse of brushes to an external source of electrical current. The coilassembly is disposed to rotate relative to the plurality of outermagnets. The plurality of coils include a plurality of printed coilsarranged in multiple coil rollers wherein a first pitch of a first setof the plurality of printed coils included within a first of themultiple coil rollers is different from a second pitch of a second setof the plurality of coil rollers included within a second of themultiple coil rollers. A plurality of inner magnets are arranged as asecond Halbach cylinder and surrounded by the plurality of coils. Themotor further includes a core element surrounded by the plurality ofinner magnets and a center rotation shaft positioned within an interiorspace circumscribed by the core element.

In yet another aspect the disclosure is directed to an apparatus for usewith a brushless motor. The apparatus includes a coil assembly having aplurality of printed coils included within multiple coil rollers of amulti-layer cylindrical coil arrangement wherein a first pitch of afirst set of the plurality of printed coils included within a firstroller of the multiple coil rollers is different from a second pitch ofa second set of the plurality of coil rollers included within a secondroller of the multiple coil rollers. The first roller forms a firstlayer of the multi-layer cylindrical coil arrangement and the secondroller forms a second layer of the multi-layer cylindrical coilarrangement. The apparatus further includes a rotor having a pluralityof outer magnets configured as a first Halbach cylinder surrounding thecoil assembly and an outer magnet housing coupled to the plurality ofouter magnets where the outer magnet housing surrounds the plurality ofouter magnets. The rotor further includes a plurality of inner magnetsarranged as a second Halbach cylinder wherein the coil assembly isinterposed between the plurality of inner magnets and the plurality ofouter magnets. An inner magnet housing of the rotor is coupled to theplurality of inner magnets. The rotor additionally includes an outputshaft surrounded by the inner magnet housing.

Also disclosed herein is a printed coil including a flexible dielectricmaterial and a patterned top conductive layer formed on a top surface ofthe flexible dielectric material. A patterned bottom conductive layer isformed on a bottom surface of the flexible dielectric material. Aplurality of printed coils are arranged in a plurality of printed coilrollers disposed to be concentrically arranged in a cylindrical shape.Each of the plurality of printed coils includes a top layer printed coildisposed within the patterned top conductive layer and a bottom layerprinted coil disposed within the patterned bottom conductive layer. Afirst coil pitch of a first set of the plurality of printed coils withina first roller of the printed coil rollers is less than a second coilpitch of a second set of the plurality of printed coils within a secondroller of the plurality of rollers such that corresponding ones of theplurality of printed coils in the first and second rollers are axiallyaligned relative to a center of the cylindrical shape.

The top layer printed coil and the bottom layer printed coil within eachof the plurality of printed coils are electrically connected through atop layer conductor extending through a via defined by the dielectriclayer.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and are merely intendedto provide further explanation of the subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

Various objects and advantages and a more complete understanding ofembodiments of the present invention are apparent and more readilyappreciated by reference to the following Detailed Description and tothe appended claims when taken in conjunction with the accompanyingDrawings wherein:

FIG. 1A illustrates a perspective view of a direct drive brushless motoradapted to include a multi-layer, variable-pitch printed coilarrangement in accordance with the disclosure.

FIG. 1B illustrates a perspective view of a direct drive brushless motorequipped with a linear encoder for providing position feedback inaccordance with the disclosure.

FIG. 2A provides an end view of a direct drive brushless motor equippedwith a linear encoder.

FIG. 2B provides a side view of the direct drive brushless motor of FIG.2A.

FIG. 2C provides a sectional view of the direct drive brushless motor ofFIG. 2A.

FIG. 3 provides a partially disassembled view of rotational componentsand non-rotational components of a direct drive brushless motor inaccordance with the disclosure.

FIG. 4A is a block diagram of an exemplary arrangement of a direct drivebrushless motor and an associated controller.

FIG. 4B is a functional block diagram is provided of a motor controlapparatus.

FIG. 5A provides a partially disassembled view a direct drive brushlessmotor which includes rotation-limiting elements configured to limitrotation of rotating components of the motor to within a desired range.

FIG. 5B provides an assembled view of the direct drive brushless motorof FIG. 5A.

FIG. 6 provides a sectional view of components of a direct drivebrushless motor incorporating a Halbach magnet arrangement.

FIG. 7 is a perspective view of a multi-layer, variable pitch flexibleprinted coil circuit assembly configured to be wound around acylindrical bobbin.

FIG. 8 shows a top view of a coil circuit assembly prior to winding ofthe assembly around a bobbin.

FIG. 9 shows a sectional view of the coil circuit assembly of FIG. 8wound around a bobbin in multiple layers, i.e., rollers.

FIG. 10 is a flowchart of a process for fabricating a multi-layer,variable pitch flexible printed circuit in accordance with thedisclosure.

FIG. 11 illustrates an adhesive transfer tape applied to the bottomlayer of all rollers in order to enable bonding of adjacent coil rollersto each other as they are wound around the bobbin and to enable bondingof the first coil roller to the bobbin.

FIG. 12 is a flowchart illustrating a coil rolling and bonding procedurein accordance with the disclosure.

FIG. 13 illustrates an exemplary coil connection path for a multi-layer,variable pitch flexible printed coil circuit in accordance with thedisclosure.

FIG. 14A is a coil circuit winding diagram illustrating an exemplarymanner in which the coils of a flexible printed coil circuit may beserially connect.

FIG. 14B illustrates an exemplary winding arrangement for a 6 pole pairimplementation.

FIG. 15 illustrates a perspective and partially transparent view of ahigh-torque, low-current brushless motor incorporating a multi-layer,variable pitch flexible printed coil in accordance with the disclosure.

FIGS. 16A, 16B and 16C respectively provide top end, side and rear endviews of the motor of FIG. 15.

FIG. 17 provides a side sectional view of a top portion of the motor ofFIG. 15.

FIG. 18 is a sectional view of the motor of FIG. 15 transverse to alongitudinal axis A.

FIG. 19 is a functional block diagram of a motor control apparatus whichmay be incorporated within a controller of an embodiment of ahigh-torque, low-current brushless motor.

FIG. 20 is a cross-sectional view of a dual rotor magnet apparatus for abrushless electric motor in accordance with an embodiment.

FIGS. 21A-21E are various views of an alternate embodiment of abrushless electric motor including a dual magnetic rotor.

In the appended figures, similar components and/or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If only the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

DETAILED DESCRIPTION

Reference will now be made in detail to embodiments of multi-layer,variable-pitch printed coil arrangements that may be used in, forexample, electromagnetic actuators and brushless motors. A descriptionof multi-layer, variable-pitch printed coil arrangements applicable to avariety of actuator designs and brushless motors is followed by adescription of particular brushless motor designs in which suchmulti-layer, variable-pitch printed coil arrangements may beincorporated.

The multi-layer, variable-pitch printed coil arrangements disclosedherein may be used in moving coil electromagnetic actuators and are oflower mass than conventional coil structures using bobbins. Such lowermass enables electromagnetic actuators to be realized with pistonstructures capable of relatively greater acceleration. Moreover, theprecision with which the multilayer printed coils described herein maybe manufactured enables actuator and brushless motor designs withreduced tolerances and correspondingly closer placement of such coils toactuator magnets, thus facilitating relatively greater force production.Finally, the multi-layer, variable-pitch printed coil arrangementsdisclosed herein may be manufactured substantially more cost effectivelythan existing actuator coils.

In one embodiment each layer of the disclosed multilayer coils isproduced by printing or otherwise depositing carbon nanotubes in a coilpattern.

Although the disclosed multi-layer, variable-pitch printed coilarrangements could be used within a variety of actuator and brushlessmotor designs, FIGS. 1-6 illustrate a particular brushless motor designcapable of accommodating such multi-layer, variable-pitch printed coilarrangements. FIGS. 7-14 illustrate particular embodiments ofmulti-layer, variable-pitch printed coil arrangements in accordance withthe disclosure. FIGS. 15-21 illustrate a particular high-torque,low-current brushless motor configured to incorporate the multi-layer,variable-pitch printed coil arrangements disclosed herein.

Multi-Layer, Variable-Pitch Printed Coils for Use with CylindricalBobbins

Attention is now directed to FIG. 7, which is a perspective view ofmulti-layer, variable pitch flexible printed coil circuit assembly 700configured to be wound around a cylindrical bobbin (not shown). Theprinted coil circuit assembly 700 includes a first set of printed coils710 on a first side 714 of the printed coil circuit assembly 700 and asecond set of printed coils 720 on a second side 724 of the printed coilcircuit assembly 700. Each of the first set of printed coils 710 isdefined by a pattern of coil winding wires and each of the second set ofprinted coils 720 is defined by a pattern of coil winding wires. Oncethe printed coil circuit assembly 700 has been fabricated in the mannerdescribed below, it is wound around a bobbin in multiple layers (or“rollers”) such that a plurality of printed coils 710 and 720 areincluded within each roller.

In one embodiment the spacing between the printed coils of a givenroller, i.e., the coil pitch) is different than the coil pitch of theother rollers of the printed coil circuit assembly 700. One purpose ofvarying coil pitch among the rollers of the assembly 700 is to ensurethat axial alignment is maintained between the coils in differentrollers once the printed coil circuit assembly 700 has been would arounda bobbin. Because the diameter of each subsequent wound layer (or“roller”) of the printed coil circuit is larger than the precedingroller, the pitch between coils is increased within each successiveroller so that corresponding coils within each roller remain inalignment along a linear axis intersecting the center of the bobbin.

Turning now to FIGS. 8 and 9, there is shown a multi-layer, variablepitch flexible printed coil circuit assembly 800 configured to be woundaround a cylindrical bobbin 804. FIG. 8 shows a top view of the coilcircuit assembly 800 prior to winding of the assembly 800 around thebobbin 804. FIG. 9 shows a sectional view of the coil circuit assembly800 wound around the bobbin 804 in multiple layers, i.e., rollers.

As shown in FIG. 8, the printed coil circuit assembly 800 includes afirst coil roller 812, a second coil roller 822 and a third coil roller832. In the embodiment of FIG. 8, the spacing between coils 810 of thefirst coil roller 812 may be less than the spacing between coils 820 ofthe second coil roller 822. Similarly, the spacing between coils 820 ofthe second coil roller 822 may be less than the spacing between coils830 of the third coil roller 832, and so on. Thus, a length of the firstcoil roller 812 will be less than the length of the second coil roller822, and the length of the second coil roller 822 will be less than thelength of the third coil roller 832. It follows that the diameter of thefirst coil roller 812 when wound around bobbin 804 will be slightly lessthan the diameter of the second coil roller 822 when wound around thebobbin 804. Making the length of the first coil roller 812 slightly lessthat the length of the second coil roller 822 in this fashion ensuresthat corresponding coils 810 and 820 in the first and second coilrollers 812 and 822 are in essentially the same angular positionrelative to the bobbin 804.

In an embodiment in which each coil roller includes 9 coils, the radiallength (L_(m)) of each coil roller is equal to 9×coil pitch, where thecoil pitch in the m^(th) roller is given by 2π(R+T_(m)/2)/9, where R isthe radius of the bobbin on which the printed coil is wound and T_(m) isthe thickness of the printed coil on the bobbin at the m^(th) roller.

This axial alignment is illustrated by FIG. 9 (not to scale), whichdepicts corresponding coils 810′, 820′ and 830′ centered at the sameangular position θ (for purposes of clarity only one coil from eachroller 812, 822, 832 is depicted). As shown in FIG. 9, an axial line Loriginating at the center of the cylindrical bobbin 804 and oriented atthe angle θ bisects the corresponding coils 810′, 820′ and 830′.

Turning now to FIG. 10, a flowchart is provided of a process 1000 forfabricating a multi-layer, variable pitch flexible printed circuit inaccordance with the disclosure. The process begins by selecting aflexible circuit material having a dielectric clad with copper on bothsides (stage 1004). This material may, for example, comprise DuPont™Pyralux® AP flexible circuit material, which is a double-sided,copper-clad laminate and an allpolyimide composite of polyimide filmbonded to copper foil. In one embodiment AP9111R Pyralux® is utilized asthe flexible circuit material so as to provide a 1 oz copper thickness(top/bottom) per one copper layer and 1 mil (0.025 mm) dielectricthickness. Of course, selection of the flexible circuit material dependsupon the gauge of the copper wire required by the printed coil design. Acopper etching process is then performed by applying, to each side ofthe flexible circuit material, a mask defining a desired printed coilcircuit pattern comprised of multiple rollers having coils of variablepitch. The unmasked copper portions of the flexible circuit material arethen exposed to acid and removed (stage 1008). In one embodiment thisetching process defines a coil circuit track width of 0.897 mm (0.035 mmcopper etch per layer) and a clearance between tracks of 5 mil (0.127mm). Again, track width and thickness will be depend upon the coppergauge wire required for the printed coil circuit being fabricated.Additional masks are then applied to areas on the top/bottom of flexiblecircuit material where copper cladding has been removed (stage 1012). Anadditional 1 oz copper is then plated onto the desired printed coilcircuit pattern on top/bottom of circuit material (stage 1016). In oneembodiment this yields a clearance of 5 mil (final coil circuit has 2 ozcopper thickness) between copper tracks. In other embodiments morecopper may be used to produce tracks of larger gauge wire while lesscopper may be used to produce smaller gauge wire (smaller copper wirediameter). The copper trace resulting from the copper plating is thencovered with a printed screen (stage 1020). Gold is then plated onto thetop copper layer of the copper trace (stage 1024). A cover layer (e.g.,LF0210) is then applied over the top layer of the last roller (i.e., thetopmost layer of the printed coil circuit when wound around the bobbin)(stage 1028). One purpose of the cover layer is to protect the coppermaterial which would otherwise be exposed to air and moisture, therebypreventing corrosion. As shown in FIG. 11, an adhesive transfer tape(e.g., 3M 9461) is then applied to the bottom layer of all rolls inorder to enable bonding of adjacent coil rolls to each other as they arewound around the bobbin and to enable bonding of the first coil roll tothe bobbin (stage 1032). This coil rolling and bonding process isdescribed in greater detail with reference to FIG. 12.

Attention is now directed to FIG. 12, which is a flowchart illustratinga coil rolling and bonding procedure 1200 in accordance with thedisclosure. As shown, the procedure 1200 is initiated by applyingadhesive material of an exemplary thickness of 1 mil. (e.g. 3M 9461) tothe bottom layer surface of the flexible circuit material (stage 1204).The first roller of the etched and plated printed circuit material isthen positioned on the outer diameter of the bobbin and then bound to itusing the adhesive material (stage 1208). The second roller of theetched and plated printed circuit material is then rolled on top of thefirst roller and adhesively bonded to it using the adhesive material(stage 1212). Similar rolling and bonding of all subsequent rollers toadjacent rollers is then repeated until the last roller has been bondedto the penultimate roller (stage 1216). The resulting rolled and bondedprinted coil circuit is then cured in an oven at approximately 110degrees C. for approximately 15 minutes (stage 1220).

Attention is now directed to FIG. 13, which illustrates an exemplarycoil connection path for a multi-layer, variable pitch flexible printedcoil circuit 2400 in accordance with the disclosure. In one embodimentthe printed coil circuit 1300 includes a plurality of coils C1R1-C9R1 ofa first roller (R1) of the circuit 1300. Each coil C1R1-C9R1 iscomprised of a top layer coil disposed in a top layer of the flexibleprinted coil circuit 1300 and a corresponding bottom layer coil disposedin a bottom layer on an opposite side of the circuit 1300. Specifically,the first coil C1R1 includes a first top layer coil (C1 _(T)) 1302, thesecond coil C2R1 includes a second top layer coil (C2 _(T)) 1312 and athird coil C3R1 includes a third top layer coil (C3 _(T)) 1322. Thecoils (C1 _(T)) 1302, (C2 _(T)) 1312, (C3 _(T)) 1322 are included withintop layer of a first roller of the circuit 1300. Similarly, the firstcoil C1R1 includes a first bottom layer coil (C1 _(B)) 1304, the secondcoil C2R2 includes a second bottom layer coil (C2 _(B)) 1314 and thethird coil C3R1 includes a third bottom layer coil (C3 _(B)) 1324included in the first roller.

As shown in FIG. 13, three coil terminals U, V and W correspond to startwires for the first bottom layer coil (C1 _(B)) 1304, the second bottomlayer coil (C2 _(B)) 1314 and the third bottom layer coil (C3 _(B)). Inan embodiment the first bottom layer coil (C1 _(B)) 1304 is seriallyconnected to the first top layer coil (C1 _(T)) 1302 through a first toplayer connection 1330 extending through a via defined by the dielectricmaterial between top and bottom layers of the printed coil circuit 1300.In like manner the second bottom layer coil (C2 _(B)) 1314 is connectedto the second top layer coil (C2 _(T)) 1312 by a second top layerconnector 1332 and both are energized by the start wire for coilterminal V. The third bottom layer coil (C3 _(B)) 1324 is connected tothe third top layer coil (C3 _(T)) 1322 by a third top layer connector1334 and both are energized by the start wire for coil terminal W.

It may be appreciated from the coil connection path illustrated in FIG.13 that coil terminal U is connected to the start wire for the firstbottom layer coil (C1 _(B)) 1304 and that this start wire is connected,by way of the first top layer connection 1330, to a finish wire 1340 (C1_(F)) of the first top layer coil (C1 _(T)) 1302 of the first coil C1R1.The fourth coil C4R1 of the first roller is wired substantiallyidentically as the first coil C1R1 and is energized by the finish wire1340 of the first top layer coil (C1 _(T)) 1302 in the same way that thefirst coil C1R1 is energized by the start wire for coil terminal U. Thesame process is repeated for coil terminals “V” and “W”. Again, aprimary purpose of the coil connection arrangement of FIG. 13 is toserially connect coils of the printed coil circuit 2400 in theillustrated manner so that the coils in adjacent rollers, which arestacked and aligned by appropriately varying coil pitch in the mannerdescribed herein, may be energized so as to create constructivelyinterfering fields.

Turning now to FIG. 14A, a coil circuit winding diagram 1400illustrating an exemplary manner in which the coils of the flexibleprinted coil circuit 1300 may be serially connected is provided. As maybe appreciated from FIG. 14, the flexible printed coil circuit may beconfigured as a 3-phase coil circuit in which the phases are controlledby the electrical signals applied to the terminals U, V, W. As indicatedby the winding diagram 1400, the first coil C1R1 is serially connectedto fourth coil C4R1 of the first roller, and the fourth coil C4R1 is inturn serially connected to a seventh coil C7R1 of the first roller Inone embodiment a finish wire 1340 (C1 _(F)) of the first top layer coil(C1 _(T)) 1302 of the first coil C1R1 runs to a fourth bottom layer coil(C4 _(B)) through an inter-coil connector 1348 (C₁₋₄). The fourth bottomlayer coil (C4 _(B)) is connected to a fourth top layer coil (C4 _(T))by a fourth top layer connector 1350. Thus, the serial connectionestablished between the first coil C1 and the fourth coil C4R1 by thefinish line of the of the first top layer coil (C1 _(T)) 1302effectively energizes both the fourth top layer coil (C4 _(T)) and afourth bottom layer coil (C4 _(B)). In similar manner a finish line ofthe fourth top layer coil (C4 _(T)) may be connected to a bottom layerof a seventh coil of the first roller. In this way a serial connectionis established between the terminal U and the first (C1R1), fourth(C4R1) and seventh (C7R1) coils of the first roller of the flexibleprinted coil circuit 1300. In a substantially identical manner serialconnections may be established between the terminal V and the second(C2R1), fifth (C5R1) and eighth (C8R1) coils of the first roller andbetween the terminal W and the third (C3R1), sixth (C6R1) and ninth(C9R1) coils of the first roller.

It may be further appreciated that the first three coils of a secondroller of the printed coil circuit 1300, i.e., C1R2, C2R2 and C2R3, maybe similarly serially connected to the coils C7R1, C8R1 and C9R1 of thefirst roller. Thus, the coils of the second and third rollers of theprinted coil circuit 1300 may be energized by the terminals U, V and Wby serially connecting the coils of the second and third rollers insubstantially the same manner as the coils of the first roller areconnected. Again, because the pitch between the coils within each rolleris varied between rollers (i.e., the coil pitch increases in roller R2relative to the coil pitch within roller R1, and increases in roller R3relative to the coil pitch within roller R2), corresponding coils withineach serially-connected roller are in axial alignment when wound arounda bobbin. This advantageously enables their respective electromagneticfields to constructively interfere.

FIG. 14B illustrates an exemplary winding arrangement for a 6 pole pairimplementation.

It may be appreciated that in other embodiments the printed coils ofeach roller may be patterned on only a single side of a flexible circuitmaterial rather than on both sides as described herein.

Brushless Motor Incorporating Multi-Layer, Variable-Pitch Printed Coils

Turning now to FIGS. 1-6, there are illustrated direct drive brushlessmotors adapted to include multi-layer, variable-pitch printed coilarrangements of the type described with reference to FIGS. 7-14. Forpurposes of clarity, various details of the multi-layer, variable-pitchprinted coil printed coils illustrated discussed with reference to FIGS.7-14 are omitted from the illustrations of the direct drive brushlessmotors describe below with reference to FIGS. 1-6.

Attention is now directed to FIG. 1A, which illustrates a perspectiveview of a direct drive brushless motor 100A adapted to include amulti-layer, variable-pitch printed coil arrangement in accordance withthe disclosure. As shown in FIG. 1A, the direct drive brushless motor100A can include a bobbin 104 and a center rotation shaft 108. The motor100A further includes a motor housing 112 surrounding a plurality ofouter magnets 116. During operation of the drive motor 100A, a dualmagnetic circuit (described below) including a plurality of multi-layer,variable-pitch printed coils 120 causes a plurality of rotationalcomponents including the bobbin 104 and center rotation shaft 108 torotate about a longitudinal axis A. The motor housing 112, plurality ofouter magnets 116 and a back plate support 114 do not rotate duringoperation of the drive motor 100A.

FIG. 1B illustrates a perspective view of a direct drive brushless motor100B equipped with a linear encoder for providing position feedback inaccordance with the disclosure. In one embodiment the direct drivebrushless motor 100B is substantially identical to the direct drivebrushless motor 100A but further includes a linear encoder assembly 150having a linear encoder feedback scale 154 and a linear feedback scaleread head 158. The linear encoder feedback scale 154 is supported by alinear scale support 162. As is discussed further below, the read head158 provides, to an external computing element or device (not shown),position feedback information concerning rotation of the plurality ofrotational components of the direct drive brushless motor 100B.

FIGS. 2A, 2B and 2C respectively provide end, side and sectional viewsof the direct drive brushless motor 100B of FIG. 1B.

Attention is now directed to FIG. 3, which provides a partiallydisassembled view of a direct drive brushless motor 300 including alinear encoder assembly for providing position feedback information inaccordance with the disclosure. In particular, the direct drivebrushless motor 300 includes a plurality of rotational components 304and a plurality of non-rotational components 308. In a particularimplementation the plurality of rotational components 304 include a setof 9 multi-layer printed coils 312 arranged to form an annularstructure. In other implementations a different number of multi-layerprinted coils 312 may be used (e.g., 6, 12 or 18 coils). Thesemulti-layer printed coils 312 may operate like brushless DC coils. Notethat other quantities may also be used such as series 9 coils orparallel 3 coils. The coils 312 are attached to a termination plate 316.

As shown in FIG. 3, the plurality of non-rotational components include aplurality of inner magnets 328 and a steel core 332. A cylindricalsleeve 340 dimensioned to circumscribe the center rotation shaft 108 issurrounded by the steel core 332. In one embodiment the plurality ofnon-rotational components 308 includes a back plate 350 configured witha plurality of circular channels for appropriately guiding and centeringthe remainder of the non-rotational components 308. As shown, circularchannel 370 of the back plate 350 receives the annular structure formedby coils 312.

During operation of the direct drive brushless motor 300, current isintroduced through the multi-layer printed coils 312 thereby creating amagnetic field having a direction that depends on the direction that thecurrent is flowing through the coils 312. The magnitude of the magneticfield corresponds to the number of turns associated with each coil andthe amperage conducted through the conductive material. It should beunderstood that any type of conductive material with varyingspecifications can be used. It should further be understood that themulti-layer printed coils 312 may be electrically connected to a powersource and/or connected together in any manner known in the electricaland mechanical arts such as by using, for example, a flexible cable(“flex cable”).

The outer magnets 116 can be, for example, substantially rectangularwith a curved cross section as shown in FIG. 3, and can be coupled to aninterior wall of the motor housing 112. For example, the outer magnets116 can be coupled to the motor housing 112 during manufacturing withvarious adhesives and/or screws. The outer magnets 116 can be adapted tomagnetically interface with the rotational components 304 when amagnetic field is present in the coils 312. Hence, by repeatedlyalternating the direction that current is flowing through the coils 312,a rotational force may be repeatedly imparted upon the rotationalcomponents 304, thus making the components 304 rotate about thelongitudinal axis A.

As noted above, the linear encoder assembly 150 includes a linearencoder feedback scale 154 and a linear feedback scale read head 158.The linear encoder feedback scale 154 is supported by a linear scalesupport 162. The linear encoder assembly 150 can also include feedbackcircuitry (not shown) along with the linear encoder feedback scale 154for indicating linear positional feedback to, for example, a controller(such as a remote computer). The linear feedback scale read head 158(e.g., a sensor, a transducer etc.), can be paired with the linearencoder feedback scale 154 that can encode position. The linear feedbackscale read head 158 can read the linear encoder feedback scale 154 andconvert the encoded position into an analog or digital signal. This inturn can then be decoded into position data by a digital readout (DRO)or motion controller (not shown in FIGS. 1-3). The linear encoderassembly 150 can work in either incremental or absolute modes. Motioncan be determined, for example, by change in position over time. Linearencoder technologies can include, for example, optical, magnetic,inductive, capacitive and eddy current. Optical linear encoders arecommon in the high resolution market (e.g., the semiconductor industrymarket and/or the biotechnology industry market) and can employshuttering/Moiré, diffraction or holographic principles. Typicalincremental scale periods can vary from hundreds of micrometers down tosub-micrometer, and following interpolation can provide resolutions asfine as 1 nm. The linear encoder assembly 150 can have a resolution inthe range of, for example, 5 microns to 50 nm. In other embodiments,finer resolution encoders can also be incorporated providing resolutionsup to, for example, 1 nm.

The linear encoder feedback scale 154 may include a series of stripes ormarkings running along a length of the linear encoder feedback scale154. During operation of the direct drive brushless motor 100B/300, thelinear feedback scale read head 158 (e.g., an optical reader) can countthe number of stripes or markings read in order to determine the currentposition of the rotational components 304 relative to the non-rotationalcomponents 308. In some instances, the recorded positional data can betransmitted to a remote device for monitoring purposes. In someinstances, a user can input one or more values to a remote device (suchas a connected computer) in order to designate an amount of rotationdesired for a particular task. These values can then be transmitted to acontroller (not shown in FIGS. 1-3) in electrical communication with thelinear encoder assembly 150 such that relative rotation of the pluralityof rotational components 304 can be adjusted according to the valuesspecified. The direct drive brushless motor 100/300 may include anynumber of electrical connections and may include any number ofelectronic control sequences. Furthermore, in other embodiments, thedirect drive brushless motor 100/300 may include any number of on-boarddigital control and/or analog circuitry known in the electrical arts.

Again referring to FIG. 3, embodiments of the direct drive brushlessmotor may utilize a dual magnetic circuit in order to obtain highertorque. Specifically, the outer magnets 320, steel housing 324 of themotor, and coils 312 form a first circuit 380. The coils 312, innermagnets 328 and center rotation shaft 108 form a second circuit 384.This arrangement is believed to provide substantially more torque thanis capable of being provided by standard brushless motors employing onlya single “outer” circuit.

As is discussed below with reference to FIG. 5, embodiments of thedirect drive brushless motor may include various rotation-limitingelements disposed to limit rotation of the rotating components 304 to adesired extent (e.g., +/−90 degrees) about the axis of rotation A (FIG.1A).

FIG. 4A shows a block diagram of an exemplary arrangement 400 of thedirect drive brushless motor 300 and an associated controller 410.During operation of the motor 300, the read head 158 of the linearencoder provides a feedback signal containing information related to theposition or angular orientation of the bobbin 104 and/or center rotationshaft 108. Controller 410 processes the feedback signal and provides acontrol signal to the motor 300 to adjust the rotation of the bobbin 104and/or center rotation shaft 108 so as to appropriately move amechanical element 420.

In one embodiment, the motor 300 sends measurements from its linearencoder to the controller 410 to indicate the precise rotationalposition about the axis A. In some configurations, the controller 410can be, for example, a Galil DMC31012 controller with built-in amplifierand a 16 bit analog output.

As is known, the controller 410, such as a servo controller, cangenerate control signals that operate the motor 300. For example, inaccordance with programmed instructions, typically in the form ofsoftware, the controller 410 can generate control signals and outputsuch control signals to the motor 300 to cause movement of a mechanicalmember or element. In one embodiment the controller 410 is programmed tocontrol the motor 300 depending on the particular application for whichthe finger 300 is being utilized. Typically, a computer (not shown) iscoupled to the controller 410 to generate and transmit software (coderepresenting a set of instructions to be executed) generated in aprogramming language to the controller 410 for the specific application.Such software, once running on the controller 410, will instruct themotor 300 to move the mechanical element 420 in a manner specific to theparticular application or task.

Turning to FIG. 4B, a functional block diagram is provided of a motorcontrol apparatus 450 which may be incorporated within the controller410 or, alternatively, within the direct drive motor 300. In theembodiment of FIG. 4B the motor control apparatus 450 operates to drivethe coils 312 of the motor 300 through sinusoidal commutation using adirect-quadrature (d-q) control process. That is, each coil phase isenergized by a continuous sinusoidal current to produce motion at aconstant torque.

During operation the motor control apparatus 450 functions to controlcurrents flowing through the coils 312. To this end a first currentsensor 454 detects a first current I_(a) flowing through one of thecoils 312 and a second current sensor 458 detects a second current I_(b)flowing through another of the coils 312. As shown, measurements of thecurrents I_(a), I_(b) and an actual position signal (θ) from the encoderread head 158 (or other position sensor operative to detect the angularposition of a rotating component of the motor 300) are supplied to a d-qtransform module 458 configured to implement a d-q transform (also knownas a Park transform). As is known, the d-q transform may be used toeffectively transform or otherwise project a three-phase system onto atwo-dimensional control space. Although in the general caseimplementation of the d-q transform requires I_(c) in addition to I_(a),I_(b) and θ, in the present embodiment the 3-phase coils of the motor300 are balanced and thus I_(c) can be reconstructed from I_(a) andI_(b).

Implementation of the Park transform enables the module 458 to expressthe set of three sinusoidal currents present on the coils 312 as adirect axis current I_(d) and a quadrature axis current I_(q). Since thePark-transformed currents I_(d), I_(q) are essentially constant, itbecomes possible to control the motor 300 by using the constant currentsI_(d), I_(q) rather than the sinusoidal signals actually supplied to themotor 300.

As shown in FIG. 4B, the control apparatus 450 includes a positioncontrol module 462 that receives a signal indicative of a referenceangle (Orel) as well as the actual position signal θ from the encoderread head 158. Based upon these values the position control module 462provides a quadrature axis reference current I_(q,ref) to a currentcontroller and inverse d-q transform module 466. The current controllerwithin the module 466 determines differences between thePark-transformed currents I_(d), I_(q) and the reference currentsI_(q,ref), I_(d,ref) and performs an inverse d-q transform based uponthe results. These operations yield command values V_(A), V_(B) andV_(C) which are then mapped into inverter switching signals S_(A+),S_(A−), S_(B+), S_(B−), S_(C+), S_(C−), by switching logic 470. A3-phase voltage source inverter 474 under the control of these switchingsignals then generates the currents I_(a), I_(b), I_(c) delivered to thecoils 312.

Attention is now directed to FIG. 5A, which provides a partiallydisassembled view of a direct drive brushless motor 500 includingrotation-limiting elements configured to limit rotation of rotatingcomponents of the motor 500 to within a desired range (e.g., 90degrees). FIG. 5B provides an assembled view of the direct drivebrushless motor 500. As shown in FIG. 5A, the direct drive brushlessmotor 500 includes a set of 9 rotating multi-layer printed coils 512arranged to form an annular structure. In other implementations adifferent number of coils 512 may be used (e.g., 6, 12 or 18 coils).These coils 512 may operate like brushless DC coils. Note that otherquantities may also be used such as series 9 coils or parallel 3 coils.The coils may be wired Y and series. The multi-layer printed coils 512are attached to a termination plate 516

As shown in FIG. 5A, the direct drive brushless motor 500 can include abobbin 504 and a center rotation shaft 508. The motor 500 furtherincludes a motor housing 510 surrounding a plurality of outer magnets516. During operation of the drive motor 500, a dual magnetic circuit(described below) including the plurality of multi-layer printed coils512 causes the rotational components of the motor 500, which include thebobbin 504 and center rotation shaft 508, to rotate about a longitudinalaxis of the motor aligned with the shaft 508. Rotation of thesecomponents may be constrained within a desired range by rotationlimiting surfaces 536 of the motor housing 510 in cooperation with arotation stopper element 538. The motor housing 510, plurality of outermagnets 516 and a back plate 540 do not rotate during operation of themotor 500.

The direct drive brushless motor 500 may further include a plurality ofnon-rotational inner magnets 528. The back plate 540 supports a centerpole structure 544 circumscribed by the non-rotational inner magnets528. The motor 500 further includes a front ball bearing 560 and rearball bearing 564. A linear encoder assembly includes a linear encoderfeedback scale 554 and a linear feedback scale read head 558. The linearencoder feedback scale 554 is supported by a motor hub 562. The readhead 558 provides, to an external computing element or device (notshown), position feedback information concerning rotation of therotational components of the direct drive brushless motor 500.

Embodiments of the direct drive brushless motor 500 may utilize a dualmagnetic circuit in order to obtain higher torque. Specifically, theouter magnets 516, center pole 544, and coils 512 form a first circuit.The multi-layer printed coils 512, inner magnets 528 and center rotationshaft 508 form a second circuit. This arrangement is believed to providesubstantially more torque than is capable of being provided by standardbrushless motors employing only a single “outer” circuit.

Turning now to FIG. 6, a sectional view of components of a direct drivebrushless motor 600 incorporating a Halbach magnet arrangement isprovided. As shown, in the embodiment of FIG. 6, a plurality of innermagnets 608 are arranged so as to form an inner Halbach cylinder and aplurality of outer magnets 612 are arranged so as to form an outerHalbach cylinder. A plurality of multi-layer printed coils 614 arearranged in the shape of a cylinder and interposed between the pluralityof inner magnets 608 and the plurality of outer magnets 612. Theplurality of inner magnets 608 and the plurality of outer magnets 612are included within dual magnetic circuits which cooperate to increasethe flux density of the magnetic field between them. Specifically, theinner magnets 608 and outer magnets 612 increase the magnetic field inthe volume in which the plurality of multi-layer printed coils 614 aredisposed. This increased flux density results in a higher output torquefor a given current level relative to conventional designs employingonly a single “outer” magnetic circuit. The remaining components of thedirect drive brushless motor 600 are substantially similar or identicalto those described with reference to FIGS. 1-5 and have been omittedfrom FIG. 6 for purposes of clarity.

Embodiments of the direct drive brushless motor described with referenceto FIGS. 1-6 may be used in connection with, for example, roboticfingers designed to emulate the range of motion of human fingers. In oneembodiment, the design of the motor takes into account that the motordoes not need to run through complete turns of 360 degrees in order tomimic the behavior of a human finger; rather, turns of 90 or 30 degreesmay be sufficient. Accordingly, in one embodiment the motor comprises apartial moving-coil rotary motor. The partial rotary motor may beadvantageously configured to have a light moving mass, therebyfacilitating a fast response and low current draw.

High-Torque, Low-Current Brushless Motor Having Multi-Layer,Variable-Pitch Printed Coils

FIGS. 15-21 illustrate a high-torque, low-current brushless motoradapted to include multi-layer, variable-pitch printed coil arrangementsof the type described with reference to FIGS. 7-14. For purposes ofclarity, various details of the multi-layer, variable-pitch printed coilprinted coils illustrated discussed with reference to FIGS. 7-14 areomitted from the illustrations of the high-torque, low-current brushlessmotor described below with reference to FIGS. 15-21.

Turning now to FIG. 15, there is shown a perspective and partiallytransparent view of a high-torque, low-current brushless motor 1500incorporating a multi-layer, variable pitch flexible printed coilarrangement in accordance with the disclosure. As shown in FIG. 15, thebrushless motor 1500 can include an motor output shaft 1508 and a motorhousing 1510 surrounding dual magnetic cylinders (not shown). The motor1500 further includes a controller housing 1512, which is depictedpartially transparently in FIG. 15. The controller housing 1512surrounds a controller 1506 and includes an end plate 1507 through whichprotrudes a servo connector interface 1509. During operation of themotor 1500, the dual magnetic cylinders and the motor output shaft 1508rotate about a longitudinal axis A. The motor housing 1510, controllerhousing 1512, end plate 1507 and a top plate 1515 do not rotate duringoperation of the motor.

Although controller 1506 is shown as being within a controller housing1512 abutting the motor housing 1510, in other embodiments thecontroller for the electric motor may be in essentially any location.For example, the controller may be located remote from the motor (e.g.,in a remote computer in network communication with the motor).

FIGS. 16A, 16B and 16C respectively provide top end, side and rear endviews of the motor 1500 of FIG. 15.

Attention is now directed to FIG. 17, which provides a side sectionalview of a top portion of the motor 1500 including the motor housing1510. The remainder of the motor 1500, including the controller housing1512, is not shown in section in FIG. 17. In one embodiment the motor1500 includes a plurality of rotational components including the motoroutput shaft 1508, a plurality of inner magnets 1708 arranged in theshape of a cylinder circumscribing the longitudinal axis A, and aplurality of outer magnets 1712 also cylindrically arranged tocircumscribe the longitudinal axis A. The plurality of inner magnets1708 are coupled to an iron core member 1709. First and second radialbearings 1709, 1711 circumscribe the output shaft 1508. An encoderfeedback read head 1720 is positioned to read an encoder feedback scalepositioned on, for example, the output shaft 1508 or on a rotatingsurface coupled to the output shaft.

The motor 1500 further includes a plurality of non-rotational componentsincluding a set of 12 multi-layer, variable pitch coils 1714 arranged toform a cylindrical structure interposed between the plurality of innermagnets 1708 and the plurality of outer magnets 1712. In otherimplementations a different number of coils 1712 may be used (e.g., 6, 9or 18 coils). The coils 1714 may operate like brushless DC coils. Thecoils 1712 may be attached to the motor housing 1510 or to a moldedstructure in turn coupled to the motor housing 1510.

Turning now to FIG. 18, a sectional view of the motor 1500 is providedtransverse to the longitudinal axis A. As shown, in the embodiment ofFIG. 17, the plurality of inner magnets 1708 are arranged so as to forman inner Halbach cylinder and the plurality of outer magnets 1712 arearranged so as to form an outer Halbach cylinder. The plurality ofmulti-layer, variable pitch coils 1714 are arranged in the shape of acylinder and interposed between the plurality of inner magnets 1708 andthe plurality of outer magnets 1712. The plurality of inner magnets 1708and the plurality of outer magnets 1712 are included within dualmagnetic circuits which cooperate to increase the flux density of themagnetic field between them. Specifically, the inner magnets 1708 andouter magnets 1712 increase the magnetic field in the volume in whichthe plurality of coils 1712 are disposed. This increased flux densityresults in a higher output torque for a given current level relative toconventional designs employing only a single “outer” magnetic circuit.

During operation of the brushless motor 1500, current is introducedthrough the coils 1714 thereby creating a magnetic field having adirection that depends on the direction that the current is flowingthrough the coils 1714. The magnetic fields produced by the coils 1714interact with the magnetic fields generated by the inner magnets and theouter magnets 1712 in order to produce a rotational force that acts onthe rotational components of the motor 1500. The magnitude of themagnetic field produced by the coils 1714 corresponds to the number ofturns associated with each coil 1714 and the amperage conducted throughthe conductive material. It should be understood that any type ofconductive material with varying specifications can be used. It shouldfurther be understood that the coils 1712 may be electrically connectedto a power source and/or connected together in any manner known in theelectrical and mechanical arts such as, for example, by using a flexcable.

The outer magnets 1712 can be, for example, substantially rectangularwith a curved cross section as shown in FIG. 18, and can be coupled to acylindrical support structure 1511 surrounded by an interior wall of themotor housing 1510. For example, the outer magnets 1516 can be coupledto the support structure 1511 during manufacturing with variousadhesives and/or screws.

As noted above, the encoder assembly includes an encoder feedback scalemounted so as to rotate with the output shaft 1508 and an encoderfeedback read head 1720. The encoder assembly can also include feedbackcircuitry (not shown) along with the encoder feedback scale forindicating positional feedback to, for example, the controller 1506 or acontroller not disposed within (such as a remote computer). The encoderfeedback read head 1720 (e.g., a sensor, a transducer etc.), can bepaired with the encoder feedback scale that can encode position. Theencoder feedback read head 1720 can read the encoder feedback scale andconvert the encoded position into an analog or digital signal. This inturn can then be decoded into position data by a digital readout (DRO)or motion controller (not shown). The encoder assembly can work ineither incremental or absolute modes. Motion can be determined, forexample, by change in position over time. Encoder technologies caninclude, for example, optical, magnetic, inductive, capacitive and eddycurrent.

The encoder feedback scale may include a series of stripes or markingsrunning along a length of the linear encoder feedback scale printed on,or affixed to, the motor output shaft 1508 or a surface coupled thereto.During operation of the brushless motor, the encoder feedback read head1720 (e.g., an optical reader) can count the number of stripes ormarkings read in order to determine the current position of therotational components of the motor 1500 relative to the non-rotationalcomponents. In some instances, the recorded positional data can betransmitted to a remote device for monitoring purposes. In someinstances, a user can input one or more values to a remote device (suchas a connected computer) in order to designate an amount of rotationdesired for a particular task. These values can then be transmitted to acontroller in electrical communication with the encoder assembly suchthat relative rotation of the plurality of rotational components can beadjusted according to the values specified. The brushless motor 1500 mayinclude any number of electrical connections and may include any numberof electronic control sequences. Furthermore, in other embodiments, themotor 1500 may include any number of on-board digital control and/oranalog circuitry known in the electrical arts.

As is known, the controller 1506, such as a servo controller, cangenerate control signals that operate the motor 1500. For example, inaccordance with programmed instructions, typically in the form ofsoftware, the controller 1506 can generate control signals and outputsuch control signals to the motor 1500 to cause movement of the shaft1508. In one embodiment the controller 1506 is programmed to control themotor 1500 depending on the particular application for which the motor1500 is being utilized. Typically, a computer (not shown) is coupled tothe controller 1506 to generate and transmit software (code representinga set of instructions to be executed) generated in a programminglanguage to the controller 1506 for the specific application. Suchsoftware, once running on the controller 1506, will instruct the motor1500 to move the shaft 1508 in a manner specific to the particularapplication or task.

Examples of computer code include, but are not limited to, micro-code ormicro-instructions, machine instructions, such as produced by acompiler, code used to produce a web service, and files containinghigher-level instructions that are executed by a computer using aninterpreter. For example, embodiments may be implemented usingimperative programming languages (e.g., C, FORTRAN, etc.), functionalprogramming languages (Haskell, Erlang, etc.), logical programminglanguages (e.g., Prolog), object-oriented programming languages (e.g.,Java, C++, etc.) or other suitable programming languages and/ordevelopment tools. Additional examples of computer code include, but arenot limited to, control signals, encrypted code, and compressed code.

Turning to FIG. 19, a functional block diagram is provided of a motorcontrol apparatus 1950 which may be incorporated within the controller1506. In the embodiment of FIG. 19 the motor control apparatus 1950operates to drive the coils 1714 of the motor 1500 through sinusoidalcommutation using a direct-quadrature (d-q) control process. That is,each coil phase is energized by a continuous sinusoidal current toproduce motion at a constant torque.

During operation the motor control apparatus 1950 functions to controlcurrents flowing through the coils 1714. To this end a first currentsensor 1954 detects a first current I_(a) flowing through one of thecoils 1714 and a second current sensor 1958 detects a second currentI_(b) flowing through another of the coils 1714. As shown, measurementsof the currents I_(a), I_(b) and an actual position signal (θ) from theencoder read head 1558 (or other position sensor operative to detect theangular position of a rotating component of the motor 1500) are suppliedto a d-q transform module 1958 configured to implement a d-q transform(also known as a Park transform). As is known, the d-q transform may beused to effectively transform or otherwise project a three-phase systemonto a two-dimensional control space. Although in the general caseimplementation of the d-q transform requires I_(c) in addition to I_(a),I_(b) and θ, in the present embodiment the 3-phase coils of the motor1500 are balanced and thus I_(c) can be reconstructed from I_(a) andI_(b).

Implementation of the Park transform enables the module 1958 to expressthe set of three sinusoidal currents present on the coils 1714 as adirect axis current I_(d) and a quadrature axis current I_(q). Since thePark-transformed currents I_(d), I_(q) are essentially constant, itbecomes possible to control the motor 1500 by using the constantcurrents I_(d), I_(q) rather than the sinusoidal signals actuallysupplied to the motor 1500.

As shown in FIG. 19, the control apparatus 1950 includes a positioncontrol module 1962 that receives a signal indicative of a referenceangle (θ_(ref)) as well as the actual position signal θ from the encoderread head 1558. Based upon these values the position control module 1962provides a quadrature axis reference current I_(q,ref) to a currentcontroller and inverse d-q transform module 1966. The current controllerwithin the module 1966 determines differences between thePark-transformed currents I_(d), I_(q) and the reference currentsI_(q,ref), I_(d,ref) and performs an inverse d-q transform based uponthe results. These operations yield command values V_(A), V_(B) andV_(C) which are then mapped into inverter switching signals S_(A+),S_(A−), S_(B+), S_(B−), S_(C+), S_(C−), by switching logic 1970. A3-phase voltage source inverter 1974 under the control of theseswitching signals then generates the currents I_(a), I_(b), I_(c)delivered to the coils 1714.

Attention is now directed to FIG. 20, which provides a cross-sectionalview of a dual rotor magnet apparatus 2000 for a brushless electricmotor in accordance with an embodiment. The dual rotor magnet apparatus2000 includes a coil assembly having a plurality of coils 2012 arrangedin the shape of a cylinder. A dual rotor includes a plurality of outermagnets 2014 configured as a first Halbach cylinder surrounding the coilassembly. A cylindrical support structure 2011 is coupled to andsurrounds the plurality of outer magnets 2014. The dual rotor furtherincludes a plurality of inner magnets 2008 arranged as a second Halbachcylinder. As shown, the plurality of coils 2012 of the coil assembly areinterposed between the plurality of inner magnets 2008 and the pluralityof outer magnets 2014. In the embodiment of FIG. 20 the plurality ofinner magnets 2008 are coupled to a core element 2009 accommodating aninterior space or chamber 2040.

The apparatus 2000 further includes a housing 2010 which surrounds therotor and the coil assembly. An output shaft 2002 coupled to, orintegral with, the rotor may protrude from an aperture defined by thehousing 2010. Radial bearings 2050, 2054 are surrounded by the coreelement 2009.

Turning now to FIGS. 21A-21E, various views of an alternate embodimentof a brushless electric motor 2100 including a dual magnetic rotor areprovided. In the embodiment of FIGS. 21A-21E, the motor 2100 includes adual magnet rotor assembly having a plurality of rotational components.Specifically, the plurality of rotational components includes a motoroutput shaft 2102, a plurality of inner magnets 2108 arranged in theshape of a first Halbach cylinder, and a plurality of outer magnets 2114also cylindrically arranged in a Halbach configuration. The plurality ofrotational components further include a cylindrical inner magnet housing2118 and cylindrical outer magnet housing 2120. The cylindrical innermagnet housing 2118 is coupled to and supports the plurality of innermagnets 2108 and surrounds the rotor shaft 2102. The outer magnethousing 2120 similarly supports the plurality of outer magnets 2114. Asshown in FIG. 21A, the motor output shaft 2102 has an inner surfacecircumscribing and defining a vacuum thru shaft 2130.

The motor 2100 further includes a plurality of non-rotational componentsincluding a motor housing 2110 and a cylindrical coil assembly 2112supported by a coil bobbin 2116. In the embodiment of FIGS. 21A-21E, thecylindrical coil assembly 2112 includes a plurality of multi-layerprinted coils arranged to form a cylindrical structure interposedbetween the plurality of inner magnets 2108 and the plurality of outermagnets 2114. That is, the plurality of outer magnets 2114 surround thecoil assembly 2112 and the coil assembly 2112 surrounds the plurality ofinner magnets 2108. The motor housing 2110 surrounds the outer magnethousing 2120 of the dual magnet rotor assembly. The output shaft 2102may protrude from an aperture defined by the motor housing 2110. Radialbearings 2150, 2154 facilitate rotation of the output shaft 2102. Anencoder feedback read head 2122 is positioned to read an encoderfeedback scale positioned on, for example, the output shaft 2102 or arotating surface coupled to the output shaft.

During operation of the dual rotor magnet apparatus 2100, the dualmagnetic cylinders and the motor output shaft 2102 rotate about alongitudinal axis circumscribed by the vacuum thru shaft 2130. The motorhousing 2110, and an end plate 2117 and a top plate 2115 arrangedsubstantially perpendicular to this longitudinal axis, do not rotateduring operation of the motor 2100. As shown, the end plate 2117 definesan aperture 2134 in communication with the vacuum thru shaft 2130 andtop plate 2115 defines an aperture circumscribing the output shaft 2102.The end plate 2117 may also support an electrical connector 2136configured to, for example, provide electrical current to the coilassembly 2112 and receive position feedback provided by the encoderfeedback read head 2122.

In one embodiment the motor 2100 may be controlled by a controllerdisposed within a controller housing (not shown) abutting the motorhousing 2110. In other embodiments the controller for the motor 2100 maybe in essentially any location. For example, the controller may belocated remote from the motor 2100 (e.g., a remote computer in networkcommunication with the motor).

Various changes and modifications to the present disclosure will becomeapparent to those skilled in the art. Such changes and modifications areto be understood as being included within the scope of the presentdisclosure. The various embodiments of the invention should beunderstood that they have been presented by way of example only, and notby way of limitation. Likewise, the various diagrams may depict anexample architectural or other configuration for the invention, which isdone to aid in understanding the features and functionality that can beincluded in the invention. The invention is not restricted to theillustrated example architectures or configurations, but can beimplemented using a variety of alternative architectures andconfigurations. Additionally, although the invention is described abovein terms of various exemplary embodiments and implementations, it shouldbe understood that the various features and functionality described inone or more of the individual embodiments are not limited in theirapplicability to the particular embodiment with which they aredescribed. They instead can, be applied, alone or in some combination,to one or more of the other embodiments of the invention, whether or notsuch embodiments are described, and whether or not such features arepresented as being a part of a described embodiment. Thus the breadthand scope of the invention should not be limited by any of theabove-described exemplary embodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; and adjectivessuch as “conventional,” “traditional,” “normal,” “standard,” “known”,and terms of similar meaning, should not be construed as limiting theitem described to a given time period, or to an item available as of agiven time. But instead these terms should be read to encompassconventional, traditional, normal, or standard technologies that may beavailable, known now, or at any time in the future. Likewise, a group ofitems linked with the conjunction “and” should not be read as requiringthat each and every one of those items be present in the grouping, butrather should be read as “and/or” unless expressly stated otherwise.Similarly, a group of items linked with the conjunction “or” should notbe read as requiring mutual exclusivity among that group, but rathershould also be read as “and/or” unless expressly stated otherwise.Furthermore, although items, elements or components of the invention maybe described or claimed in the singular, the plural is contemplated tobe within the scope thereof unless limitation to the singular isexplicitly stated. For example, “at least one” may refer to a single orplural and is not limited to either. The presence of broadening wordsand phrases such as “one or more,” “at least,” “but not limited to”, orother like phrases in some instances shall not be read to mean that thenarrower case is intended or required in instances where such broadeningphrases may be absent.

The word “exemplary” is used herein to mean “serving as an example orillustration.” Any aspect or design described herein as “exemplary” isnot necessarily to be construed as preferred or advantageous over otheraspects or designs.

It should be understood that the specific order or hierarchy of steps inthe processes disclosed herein is an example of exemplary approaches.Based upon design preferences, it is understood that the specific orderor hierarchy of steps in the processes may be rearranged while remainingwithin the scope of the present disclosure. The accompanying methodclaims present elements of the various steps in a sample order, and arenot meant to be limited to the specific order or hierarchy presented.Implementation of the techniques, blocks, steps and means describedabove may be done in various ways. For example, these techniques,blocks, steps and means may be implemented in hardware, software, or acombination thereof. For a hardware implementation, the processing unitsmay be implemented within one or more application specific integratedcircuits (ASICs), digital signal processors (DSPs), digital signalprocessing devices (DSPDs), programmable logic devices (PLDs), fieldprogrammable gate arrays (FPGAs), processors, controllers,micro-controllers, microprocessors, other electronic units designed toperform the functions described above, and/or a combination thereof.

Also, it is noted that the embodiments may be described as a processwhich is depicted as a flowchart, a flow diagram, a data flow diagram, astructure diagram, or a block diagram. Although a flowchart may describethe operations as a sequential process, many of the operations can beperformed in parallel or concurrently. In addition, the order of theoperations may be re-arranged. A process is terminated when itsoperations are completed, but could have additional steps not includedin the figure. A process may correspond to a method, a function, aprocedure, a subroutine, a subprogram, etc. When a process correspondsto a function, its termination corresponds to a return of the functionto the calling function or the main function.

Furthermore, embodiments may be implemented by hardware, software,scripting languages, firmware, middleware, microcode, hardwaredescription languages, and/or any combination thereof. When implementedin software, firmware, middleware, scripting language, and/or microcode,the program code or code segments to perform the necessary tasks may bestored in a machine readable medium such as a storage medium. A codesegment or machine-executable instruction may represent a procedure, afunction, a subprogram, a program, a routine, a subroutine, a module, asoftware package, a script, a class, or any combination of instructions,data structures, and/or program statements. A code segment may becoupled to another code segment or a hardware circuit by passing and/orreceiving information, data, arguments, parameters, and/or memorycontents. Information, arguments, parameters, data, etc. may be passed,forwarded, or transmitted via any suitable means including memorysharing, message passing, token passing, network transmission, etc.

In conclusion, the present invention provides, among other things,reduced-diameter linear electromagnetic actuators and reduced-costmethods of manufacturing those electromagnetic actuators. Those skilledin the art can readily recognize that numerous variations andsubstitutions may be made in the invention, its use and itsconfiguration to achieve substantially the same results as achieved bythe embodiments described herein. Accordingly, there is no intention tolimit the invention to the disclosed exemplary forms. Many variations,modifications and alternative constructions fall within the scope andspirit of the disclosure as expressed in the claims.

1. A printed coil assembly, comprising: a flexible dielectric material;a patterned top conductive layer formed on a top surface of the flexibledielectric material; and a patterned bottom conductive layer formed on abottom surface of the flexible dielectric material, the patterned topconductive layer and the patterned bottom conductive layer forming aplurality of printed coils arranged in a plurality of printed coilrollers disposed to be concentrically arranged in a cylindrical shape;wherein each of the plurality of printed coils includes a top layerprinted coil disposed within the patterned top conductive layer and abottom layer printed coil disposed within the patterned bottomconductive layer; wherein a first coil pitch of a first set of theplurality of printed coils within a first roller of the printed coilrollers is less than a second coil pitch of a second set of theplurality of printed coils within a second roller of the plurality ofrollers such that corresponding ones of the plurality of printed coilsin the first and second rollers are axially aligned relative to a centerof the cylindrical shape.
 2. The printed coil assembly of claim 1wherein the top layer printed coil and the bottom layer printed coilwithin each of the plurality of printed coils are electrically connectedthrough a top layer conductor extending through a via defined by theflexible dielectric material.
 3. The printed coil assembly of claim 2wherein a first bottom layer printed coil, a second bottom layer printedcoil and a third bottom layer printed coil are respectively (i) includedwithin a first printed coil, a second printed coil and a third printedcoil of the plurality of printed coils, and (ii) connected to a firstterminal start line, a second terminal start line and a third terminalstart line.
 4. The printed coil assembly of claim 3 wherein a first toplayer printed coil, a second top layer printed coil and a third toplayer printed coil are respectively (i) included within the firstprinted coil, the second printed coil and the third printed coil of theplurality of printed coils and (ii) electrically connected to a fourthprinted coil, a fifth printed coil and a sixth printed coil of theplurality of printed coils.
 5. The printed coil assembly of claim 1further including a cylindrical bobbin around which the printed coilrollers are arranged.
 6. The printed coil assembly of claim 1 whereinthe first set of the plurality of printed coils includes first, second,third, fourth, fifth and sixth printed coils and wherein a first finishwire of the first printed coil is electrically connected to the fourthprinted coil, a second finish wire of the second printed coil iselectrically connected to the fifth printed coil, and a third finishwire of the third printed coil is electrically connected to the sixthprinted coil.
 7. The printed coil assembly of claim 6 further includinga first inter-coil connector defined within the dielectric material, thefirst inter-coil connector establishing an electrical connection betweenthe first finish wire and the fourth printed coil.
 8. The printed coilassembly of claim 1 further including adhesive transfer tape applied tothe patterned bottom conductive layer.
 9. The printed coil assembly ofclaim 1 wherein the patterned top conductive layer includes a firstcopper layer clad to the top surface of the flexible dielectric materialand a first gold layer plated to the first copper layer.
 10. The printedcoil assembly of claim 9 wherein the patterned bottom conductive layerincludes a second copper layer clad to the bottom surface of theflexible dielectric material and a second gold layer plated to thesecond copper layer.
 11. A printed coil arrangement, comprising: aflexible circuit material rolled into concentric printed coil rollerswherein each of the plurality of concentric printed coil rollersincludes a plurality of printed coils and wherein a pitch of theplurality of printed coils within each one of the plurality of printedcoil rollers is different from a pitch of the plurality of printed coilswithin any other of the plurality printed coil rollers, the pitches ofthe printed coils within each of the plurality of coil rollers beingselected such that corresponding ones of the plurality of printed coilsin each of the plurality of printed coil rollers are axially alignedrelative to a center of a cylindrical shape into which the flexiblecircuit material is rolled; a bobbin; and an adhesive layer attached toan outer surface of the bobbin and a bottom surface of an innermost oneof the plurality of concentric printed coil rollers.
 12. The printedcoil arrangement of claim 11 wherein the adhesive layer is also attachedto a bottom surface of each the plurality of concentric printed coilrollers and binds adjacent ones of the plurality of concentric printedcoil rollers.
 13. The printed coil arrangement of claim 11 wherein theflexible circuit material includes a patterned top conductive layerformed on a top surface of a flexible dielectric material and apatterned bottom conductive layer formed on a bottom surface of theflexible dielectric material, the patterned top conductive layer and thepatterned bottom conductive layer forming the plurality of printed coilsof each of the plurality of concentric printed coil rollers.
 14. Theprinted coil arrangement of claim 13 wherein each of the plurality ofprinted coils includes a top layer printed coil disposed within thepatterned top conductive layer and a bottom layer printed coil disposedwithin the patterned bottom conductive layer.
 15. The printed coilarrangement of claim 11 wherein a first coil pitch of a first set of theplurality of printed coils within a first roller of the printed coilrollers is less than a second coil pitch of a second set of theplurality of printed coils within a second roller of the plurality ofrollers.
 16. A method of fabricating a printed coil arrangement, themethod including: applying, to a top conductive layer of a flexiblecircuit material and to a bottom conductive layer of a flexible circuitmaterial, one or more masks defining a desired printed coil circuitpattern where the desired printed coil circuit pattern includes multiplerollers having printed coils of variable pitch and wherein the flexiblecircuit material further includes a flexible dielectric layer sandwichedbetween the top conductive layer and the bottom conductive layer;exposing unmasked portions of the top conductive layer of the flexiblecircuit material and the bottom conductive layer of the flexible circuitmaterial to acid and removing the unmasked portions of the topconductive layer and the bottom conductive layer; applying additionalmasks to the unmasked portions of the top conductive layer and thebottom conductive layer; plating additional conductive material onto thedesired printed coil pattern; covering a conductive trace resulting fromthe plating with a printed screen; and plating one of gold and adifferent conducive material onto the additional conductive material ofthe conductive trace.
 17. The method of claim 16 further includingapplying a cover layer over a portion of the top conductive layerassociated with a last of the multiple rollers.
 18. The method of claim16 further including applying, after the plating one of gold and adifferent conducive material, an adhesive transfer tape to the bottomconductive layer.
 19. The method of claim 18 further including: windingthe multiple rollers around a bobbin; bonding, with the adhesivetransfer tape, adjacent rollers to each other as the multiple rollersare wound around the bobbin; bonding, with the adhesive transfer tape,an innermost one of the multiple rollers to an outer surface of thebobbin.
 20. A method of fabricating a printed coil arrangement, themethod including: etching a flexible circuit material into a pluralityof coil rollers wherein each of the plurality of coil rollers includes aplurality of printed coils and wherein a pitch of the plurality ofprinted coils within each one of the plurality of printed coil rollersis different from a pitch of the plurality of printed coils within anyother of the plurality printed coil rollers, the pitches of the printedcoils within each of the plurality of coil rollers being selected suchthat corresponding ones of the plurality of printed coils in each of theplurality of printed coil rollers are axially aligned relative to acenter of a cylindrical shape into which the flexible circuit materialis rolled; applying an adhesive material to a bottom surface of theflexible circuit material; positioning a first coil roller of theplurality of printed coil rollers on an outer surface of a bobbin andbonding the first coil roller to the outer surface using the adhesivematerial; rolling remaining rollers of the plurality of printed coilrollers onto the first coil roller; bonding adjacent printed coilrollers of the plurality of printed coil rollers to each other using theadhesive material, thereby creating a rolled and bonded printed coilcircuit; and curing the rolled and bonded printed coil circuit in anoven. 21-26. (canceled)